Most LG smartphones have the LG keyboard installed and set as standard, but other keyboards such as SwiftKey or Gboard can also be installed and used.

Note: In order to change/use a new standard keyboard, it must first be activated.

Android 9 | LG UX 9.0
Step 1:  Open the  Settings
Step 2:  Tap on  General
Step 3:  Tap on  Language & keyboard
Step 4:  Tap on  Default keyboard
Step 5:  Choose desired  keyboard
  1. Open the Settings
  2. Tap on General
  3. Tap on Language & keyboard
  4. Tap on Default keyboard
  5. Choose desired keyboard

LG Instructions